A composition containing a polyarylene sulfide resin represented by a polyphenylene sulfide resin (hereinafter sometimes abbreviated to PPS) of thermoplastic resins has properties, which are suited for use as engineering plastics capable of serving as a substitute for parts composed of conventional metal, such as excellent heat resistance, chemical resistance, electrical insulation properties, moist heat resistance, and flame retardancy as well as high barrier properties against various oils or gases, and the composition is mainly used in various electronic parts, mechanical parts, and automobile parts as materials for injection molding and extrusion molding. Furthermore, a polyphenylene sulfide resin composition is applied for piping parts through which oil or hot water pass, and piping parts of a hot-water heater, through which hot water passes, or peripheral parts thereof by making use of these characteristics.
However, when a PPS resin composition is used as a material of piping parts of a hot-water heater, hot water heated to about 80° C. passes therethrough, and thus causing a problem that a molded article undergoes deformation, resulting in leak of water from the assembling portion, i.e. poor creep characteristics. Therefore, there arose a problem that product design is restricted, and the PPS resin composition cannot be used in parts, through which a large amount of hot water passes, and to which an inner pressure is applied.
In order to substitute a metal member for fluid piping, installed outdoors, for the PPS resin composition, it has recently been required to maintain excellent various characteristics in a wide ambient operating temperature range (from low temperature (about −20° C.) to high temperature (temperature based on the assumption of hot water)) and to have durability.
A PPS resin has low toughness as compared with other engineering plastics such as nylon and PBT, and a technique for mixing the PPS resin with an elastomer component is generally used so as to impart toughness in a particularly low temperature range. In contrast, mixing with the elastomer component may cause drastic deterioration of heat resistance of the PPS resin composition due to low glass transition temperature of the elastomer component per se.
Patent Literature 1 discloses a PPS resin composition including specific amorphous thermoplastic resins such as a polyetherimide (hereinafter sometimes abbreviated to PEI) resin and a polyethersulfone (hereinafter sometimes abbreviated to PES) mixed therein, together with an olefin elastomer.
Patent Literatures 2 to 5 disclose, for example, compositions including a PPS resin and a PEI resin or a PES resin mixed therein.
Patent Literature 6 discloses a melt-kneading method of a thermoplastic resin having a reactive functional group in which elongational flow field is utilized.